Physics Experiments Urgent... Thanks

It will stop boiling at first, and it will boil again when cold water is poured.

There is a refrigerator (preferably a freezer glass), equipment: 2 water cups (100ml disposable cups are always available.) ), a small amount of salt, 3 thermometers, 1 bottle of purified water (i.e. distilled water) (if you don't distill it yourself, you will buy it--.)

Steps: 1To make the brine, a thermometer is placed in two glasses of water. Record the initial temperature (probably a little lower than room temperature).

3.Throw the thermometer in the refrigerator and look at the freezing temperature, (my house is -4,) 4Look at the thermometer in the cup every two minutes and write it down until there is a cup that freezes completely, 5

Draw a three-line n column **, the first column 2 and 3 lines are written with pure water and salt water respectively. In the second column, write "0 minutes", "2 minutes", "4 minutes" in the first line, and write the temperature in the second or third line

1. The water will boil.

2. Experiment: Which one freezes faster, pure water or salt water.

Purpose of the experiment: Through experiments...

Experimental equipment: two cups, refrigerator, etc.

Materials: water, salt, etc.

Procedure:...

Conclusion: . .

Just fill it out yourself.

1.(pressure reduction) water re-boiling2Put the same quality of pure water and salt water in a container of the same material and shape, put it in the refrigerator freezer and adjust it to a low temperature (pure water freezes first).

1**。2 Materials: beaker, refrigerator, salt, water.

Operation method: Pour the same amount horizontally into a beaker, take the salt as the control group, and the salt without the salt as the experimental group. After an hour, compare the experimental combination control group and observe the records.

The water will boil again.

Place a glass of water in the refrigerator at the same time as a glass of saline, observe every five minutes, and record the time.

take g=10m s

1) The pressure of the wood block on the plank sliding friction n

2) Compare 1 and 2

3) The sliding friction is proportional to the positive pressure and has nothing to do with the contact area.

Hope you will.

1) Data in the table.

Number of experiments on the pressure of the wood block on the plank and the sliding friction.

1 Newton 4 Newtons.

1 Newton 4 Newtons.

1 Newton 8 Newton.

2) Comparing the experimental data of the first and second passes, it can be found that the friction force is independent of the contact area.

3) Comparing the data of the first experiment, it can be concluded that the coefficient of friction is independent of the amount of pressure.

Principle analysis: Since the mass and volume of the two balls are equal and coated with paint, they cannot be directly distinguished from the appearance, nor can they be distinguished by the form of buoyancy.

Considering that the material of aluminum and copper is different, the density of copper is larger, so for such two balls, the moment of inertia of the hollow copper ball on the central axis is larger, if the two balls are rotated with the same force in the smooth horizontal plane, then the angular velocity of the copper ball with greater moment of inertia must be smaller.

Experimental steps: 1. Use the same force to rotate the two balls in turn on a smooth horizontal plane.

2. Observe the speed of rotation of the two balls (angular velocity).

Conclusion: The hollow copper ball with a small angular velocity is a solid aluminum ball, and the solid aluminum ball with a larger angular velocity is larger.

This is the college method.

If it is a secondary school content, it can only be distinguished by the difference in specific heat capacity, that is, let them have the same initial temperature at room temperature, and then put them in boiling water at 100 degrees Celsius for a while. Then put the ball into the water at a certain temperature, and compare the increase in water temperature to tell which is the aluminum ball and which is the copper ball.

The identification methods of density, mass, and volume are no longer available.

You can try to identify it from the perspective of specific heat capacity, because aluminum is the same, and copper is the same, so when the heat absorption is the same, the temperature change of copper is much higher than that of aluminum.

Therefore, you can prepare hot water of the same quality and submerge the copper ball and aluminum ball in it respectively until the temperature of the two does not change, and measure the water temperature. The high water temperature is the copper ball, and the low one is the aluminum ball.

If you don't know, please ask.

Tap to listen to the sound, the hollow copper ball has a resonant sound.

A cup that absorbs water.

Think: Cover a burning candle with a glass, what happens to the inside of the candle after the candle flame is extinguished?

Ingredients: 1 glass (higher than a candle), 1 candle, 1 flat bottom plate, 1 lighter, some water.

Operation: 1Light the candle and place a few drops of wax oil on the plate** in order to hold the candle in place.

2.Fill the dish with water about 1 cm high.

3.Use a glass upside down on the candle.

4.Observe the burning of the candle and the change in the water level in the plate

1.When the air (oxygen) in the glass is consumed, the candle flame is extinguished.

2.When the candle is extinguished, the water level in the cup will gradually rise.

Creation: Can you automatically collect other solutions from an empty container?

The bulb is connected in series with the fixed value resistance r, the sliding rheostat is adjusted to make the voltage representation number at both ends of the bulb in parallel when the number is U, then the voltage at both ends of the fixed value resistance is measured with a voltmeter, the current is calculated according to Ohm's law, that is, the rated current of the small bulb is measured, the rated power of the small bulb is measured, the experimental circuit is shown in the figure to calculate the current in the circuit i=u r, and then the rated power of the bulb is calculated p=ui=u u r

After the change, 3, pour out a part of the water in the graduated cylinder in the beaker, measure the mass of pouring water and beaker m2, then the mass of water is (m2-m1).

4. Read out the volume of the remaining water in the graduated cylinder v2, then the volume of poured water is (v1-v2) and finally calculate p = (m2-m1) (v1-v2) because in the third part, the water in the graduated cylinder is easy to be unclean, so that the inner wall of the graduated cylinder is stained with water droplets, so that the quality of the water becomes smaller, and the density becomes smaller.

Hope it helps

1. Experiment on the relationship between current and voltage and resistance of resistance. 2. (voltammetry) lamp resistance measurement experiment. 3. Measure the electric power of the bulb, and measure the dry line, and apply the super-gradual experiment.

2. Experimental principle of measuring bulb resistance (voltammetry Luzhou method): r= . Experimental principle of measuring the electric power of the bulb: p=ui.

3. Experimental circuit diagram of the relationship between current and voltage and resistance of the resistor: Figure 1.

Circuit diagram of bulb resistance test bulb electric power test: Figure 2.

Note: The connection sequence of each component in the physical diagram must be consistent with the circuit diagram. The circuit diagram and the experimental diagram should be marked with letters to distinguish each component. The positive and negative binding posts of the two tables should be connected correctly.

How to choose the range of the voltmeter: It is determined according to the rated voltage value of the bulb provided by the question. It is determined according to the binding post connected to the voltmeter dial of the title below. Determined by the voltage value measured in the inscription data** below.

How to choose the range of the ammeter: It is determined according to the binding post connected to the dial of the ammeter below. It is determined from the current value measured in the data sheet below. The current passed by a bulb is about, so when measuring the bulb ammeter, the ammeter is generally selected as 0-. ）

1 moment of inertia is not only related to the mass distribution, but also related to the position of the shaft, 2 in the moment of inertia measurement experiment, the moment of inertia of the bracket must be measured in advance and subtracted from the results. If the moment of inertia of the bracket is not subtracted, then the moment of inertia of the object to be measured in the result will inevitably increase. The resulting error increases.

The true value is the true value of this physical quantity, which is the average of the measured data and uses it as our estimation of the true value.

The standard deviation of measurement is the deviation of the direct measurement quantity, which is only the accuracy of the experimental measurement, and the deviation of the average value is the deviation of the data processing results, which is not only accurate in the experimental measurement, but also in the process of data processing.

Error is a deviation, i.e., the deviation of the measured quantity from the true value; Uncertainty is a range that represents the range within which the error is likely to exist under this condition.

I hope the subject will adopt it.